1. Field of the Invention
This invention relates to the storage, dispensing and use of joint compound, or drywall mud, in building applications and more particularly, to a drywall mud storage and distribution system which is characterized in a first embodiment by a drywall mud container and a pump mounted on a portable frame, with a flexible conduit connecting the pump to a portable pressure tank. A second conduit leads from the pressure tank for dispensing drywall mud through a pressure-sensitive lower valve to a trigger-operated tape and mud dispensing device or the like, on demand. An additional conduit system includes a handle-operated upper valve for selectively dispensing drywall mud from the pressure tank to a mud dispensing tray. The pressure tank is fitted with an internal diaphragm and a pressure switch to facilitate periodic resupply of drywall mud from the mud container into the lower portion or chamber of the pressure tank, and then through the upper and lower valves and conduits to the tape and mud dispensing device and mud dispensing tray, on demand. In a preferred embodiment of the invention the portable frame carrying the mud container is mounted on wheels for efficient portability and the drywall mud is supplied to the pressure tank from the mud container by operation of a positive displacement or progressive cavity pump, which is typically operated by an electric motor and gearbox.
A costly problem in the mixing and dispensing of drywall mud in building applications is maintaining the drywall mud at a desired consistency over a long period of time during an extensive "taping and floating" operation. Powdered drywall compound is typically mixed with water to form the desired drywall mud slurry, which must be prepared in a selected consistency for proper application to the walls and ceiling of a structure. If the drywall mud is too "stiff", it will not flow properly and proper application is rendered difficult or impossible. However, if the water content of the drywall mud is excessive, the mud will flow from the ceiling and walls and cannot therefore be properly applied. Furthermore, as time progresses, even if the drywall mud is initially mixed to a desired consistency, the water content decreases through evaporation and the mud has a tendency to stiffen, thereby rendering proper and uniform application difficult or impossible.
2. Description of the Prior Art
Various types of drywall mud containing and dispensing apparatus are known in the art. Typical of these devices is the "Self-Contained Drywall Taper" detailed in U.S. Pat. No. 2,815,142, dated Dec. 3, 1957, to R. G. Ames. The device includes a tubular tape application apparatus which is fitted with a mud-containing chamber, a rotatable roll of tape and a dispensing head for applying the tape in a constant motion and applying mud on top of the tape. U.S. Pat. No. 3,707,427, dated Dec. 26, 1972, to E. J. Erickson, details a "Dispensing Gun For Wallboard Tape and Joint Compound". The dispensing gun includes a hand-held apparatus having a dispensing chamber, through which wallboard tape is passed from a tape roll. The tape enters an inlet opening in the chamber and passes through the inlet opening to an outlet opening which is associated with a tear-off blade, so that the operator may apply pressure through the hand-held unit to the blade, in order to properly apply tape to the wallboard. The dispensing chamber contains a quantity of compound, over which the wallboard-contacting side of the tape passes. A "Taping Gun" is detailed in U.S. Pat. No. 4,003,781, dated Jan. 18, 1977, to Roger W. Holsten. The taping gun or tool is designed to dispense tape for drywall and includes a handle-like support device having a container mounted thereon and adapted to receive cement material therein. The container is provided with first and second tape openings and a roll of tape is rotatably mounted on the support and extends through the first tape opening and along the interior surface of the tool. The first roller is rotatably mounted on the forward end of the container and is adapted to receive the tape to applying the tape with cement to the drywall. A tape cutter assembly is pivotally mounted on the forward end of the container and is movable from the tape cutting position to a non-cutting position. A spring is operatively connected to the tape cutter assembly for maintaining the assembly in its cutting position. U.S. Pat. No. 4,080,240, dated Mar. 21, 1978, to Norman A. Dysart, details a "Coded Tape Applicator for Dry Walls". The applicator is designed for dispensing a tape coated with an adhesive compound onto a drywall and particularly, along the abutting margins of the drywall panels. The applicator includes a housing containing a reel from which the tape is dispensed and a chamber through which the tape passes. The chamber is fitted with a distributor nozzle which applies a drywall compound to the tape and the housing carries a set of applicator wheels, over which the tape passes as the wheels press the tape flat against the abutting margins of the coplanar panels. A "Dry Wall Taping Machine Having An Improved Applicator Head" is detailed in U.S. Pat. No. 4,208,239, dated Jun. 17, 1980, to Harold M. Lass. The device is hand-operated and includes a tubular body designed for holding by the operator, with a tape applicator head portion at one end. The tool is supplied with drywall tape cement from a supply under pressure and a supply of drywall tape is carried from the main body of the applicator. The tape is fed through the applicator head onto the wall joint to be taped. In the applicator head, a pair of tape drive wheel portions engage the tape and press it against the wall for taping a seam between the two adjacent sections of drywall. Another "Tape Applicator" is detailed in U.S. Pat. No. 4,652,331, dated Mar. 24, 1987, to Richard Plasencia. The applicator includes an adhesive-dispensing nozzle adapted to be mounted on a caulking gun and an applicator roll is mounted adjacent the applicator nozzle. The nozzle is provided with an opening adjacent an inlet for receiving a tape for passage through the nozzle from the opening to the nozzle outlet, wherein the adhesive is applied to one side of the tape. The nozzle has a spring-biased, adjustable gate member to control application of the adhesive and to act as a pressure relief valve if the pressure in the caulking gun becomes too great.
It is an object of this invention to provide a new and improved drywall mud storage and distribution system which is portable and capable of maintaining a large volume of drywall mud at a selected consistency for immediate application at at least one dispensing location.
Another object of the invention is to provide a drywall mud storage and distribution system which includes a drywall mud container and a pump mounted on a portable frame and connected by a flexible conduit to a pressure tank fitted with a mud-dispensing conduit system to facilitate dispensing of drywall mud at a selected dispensing point or points.
Still another object of this invention is to provide a new and improved drywall mud storage and distribution system which includes a frame mounted on wheels; a mud container mounted on the frame for mixing drywall mud in selected quantities; a pump also mounted on the frame for pumping drywall mud from the mud container through a flexible conduit to a portable pressure tank which may be included on or separate from the frame; a suitable pressure control system for automatically dispensing drywall mud from the mud container to the pressure tank responsive to a preselected pressure drop in the pressure tank; and a suitable dispensing conduit and valve system for dispensing drywall mud from the pressure tank to load a mud-dispensing apparatus such as a trigger-operated tape and mud dispensing apparatus responsive to depression of the application trigger on the apparatus.
A still further object of this invention is to provide a drywall mud storage and distribution system which is characterized by a portable frame; a mud container and pump mounted on the frame and a portable pressure tank provided separately from the frame and connected to the pump by a flexible conduit; and further including a second conduit system leading from the pressure tank and fitted with upper and lower valves. Drywall mud mixed and stored in the mud container is automatically transferred to the pressure tank through the flexible conduit by operation of the pump, and drywall mud of desired consistency is dispensed from the pressure tank through a pressure-sensitive lower valve to load a trigger-operated tape and mud dispensing device responsive to depression of an application trigger on the device. Drywall mud is also dispensed from the pressure tank to a mud dispensing tray on demand, by manual operation of the upper valve.